title: Saccharin enhances neurite extension by regulating organization of the microtubules.
abstract: OBJECTIVE
  In the present study, we found that saccharin, an artificial calorie-free sweetener, promotes neurite extension in the cultured neuronal cells. The purposes of this study are to characterize the effect of saccharine on neurite extension and to determine how saccharin enhances neurite extension.
  
  
  METHODS
  The analyses were performed using mouse neuroblastoma N1E-115 cells and rat pheochromocytoma PC12 cells. Neurite extension was evaluated by counting the cells bearing neurites and measuring the length of neurites. Formation, severing and transportation of the microtubules were evaluated by immunostaining and western blotting analysis.
  
  
  RESULTS
  Deprivation of glucose increased the number of N1E-115 cells bearing long processes. And the effect was inhibited by addition of glucose. Saccharin increased the number of these cells bearing long processes in a dose-dependent manner and total neurite length and longest neurite length in each cell. Saccharin also had a similar effect on NGF-treated PC12 cells. Saccharin increased the amount of the microtubules reconstructed after treatment with nocodazole, a disruptor of microtubules. The effect of saccharin on microtubule reconstruction was not influenced by dihydrocytochalasin B, an inhibitor of actin polymerization, indicating that saccharin enhances microtubule formation without requiring actin dynamics. In the cells treated with vinblastine, an inhibitor of microtubule polymerization, after microtubule reorganization, filamentous microtubules were observed more distantly from the centrosome in saccharin-treated cells, indicating that saccharin enhances microtubule severing and/or transportation.
  
  
  CONCLUSIONS
  These results suggest that saccharin enhances neurite extension by promoting microtubule organization.
authors.affiliation: Department of Basic Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Obihiro Hokkaido, Japan.
authors.forename: Hiroo
authors.initials: H
authors.lastname: Yamashita
authors.forename: Yoshikage
authors.initials: Y
authors.lastname: Muroi
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Ishii
mesh_terms: D000818:Animals; D002460:Cell Line; D005947:Glucose / Q000378:metabolism; D051379:Mice; D008870:Microtubules / Q000187:drug effects* / Q000378:metabolism* / Q000648:ultrastructure; D016501:Neurites / Q000187:drug effects* / Q000378:metabolism* / Q000648:ultrastructure; D016716:PC12 Cells; D051381:Rats; D012439:Saccharin / Q000378:metabolism*; D013549:Sweetening Agents / Q000378:metabolism*
chemical_list: D013549:Sweetening Agents; D012439:Saccharin; D005947:Glucose
keywords: Microtubule; Neurite extension; Saccharin